New Car: 2012 Buick LaCrosse eAssist

It’s been a very short time since the revampedBuick LaCrosse debuted, but it has already seen plenty of changes, including a reordered engine lineup and major suspension upgrades. For its third model year, the LaCrosse’s base engine—a 2.4-liter four-cylinder—will get some help from an upgraded transmission and an electric motor. Combined with the car’s aero-enhancing tweaks, GM says the electric motor could boost EPA-estimated fuel economy from 19 mpg city and 30 highway to 25/37. Oh, and did we mention it’ll be standard equipment?

A few years ago, GM sold mild hybrid versions of the Chevrolet Malibu and Saturn Aura that essentially replaced the alternator with an electric motor. This arrangement allowed the engine to turn off at stops—while keeping the accessories running—but couldn’t propel the car on electricity alone. The new setup, called eAssist, is fundamentally the same thing, but heavily upgraded. It uses a lithium-ion battery pack in place of the old nickel-metal hydride unit and delivers up to 15 hp of electrical assist, three times more than before. The boost in power should make eAssist more useful than the previous system. GM says it can cut fuel to the engine during deceleration, as opposed to the mild-hybrid setup that only cut fuel and shut the engine down when the car was stopped. Like the old system, the electric motor starts the gas engine when the driver takes his foot off the brake, but cannot propel the vehicle on its own.

The battery pack is located behind the rear seats and cooled by an electric fan that draws air from the cabin. The gas engine charges it, as does a regenerative-braking system that also has a function to keep the car from rolling back on inclines while the engine is off. The battery pack weighs about 65 pounds and reduces trunk space by 2.4 cubic feet, to 10.9, although it sits to one side and still allows for part of the rear seat to fold. Engineers say that the overall weight of the LaCrosse 2.4 will remain the same, as they have compensated for the added pounds in other areas, primarily by swapping the spare tire for an inflation kit.

The aforementioned aerodynamic tweaks also will help the LaCrosse reach those lofty fuel-economy estimates. The LaCrosse eAssist gets new aero-optimized underbody trays and active flaps behind the front fascia. These flaps close at higher speeds, reducing drag by forcing air to flow around the vehicle rather than get caught up in the engine compartment. Furthermore, eAssist will debut a new generation of the six-speed automatic transmission, with reduced internal friction and quicker shifts. Buick says that the additional power of the electric motor will reduce the need for downshifts, which we hope holds true—the busy transmission was our main complaint during our first drive of the four-cylinder LaCrosse. Finally, low-rolling-resistance Michelin tires will make their way onto the car. Inside, the only change will be the addition of an Eco gauge in the cluster.

Buick hasn’t given final pricing for the 2012 LaCrosse eAssist, saying only that the car will cost around $30,000. For reference, the 2011 2.4-liter started at $27,745. If GM’s fuel-economy claims prove true, Buick could have a cost-effective fuel-sipping hybrid-fighter on its hands when the eAssist goes on sale in the middle of next year.